The propane furnace flame sensor is a crucial component in the safe and efficient operation of a propane furnace. Its primary function is to confirm that the ignition source has ignited the gas at the first burner and that the flame has traveled all the way across to the last burner. This is achieved through the use of a stainless steel rod, typically about the size of a 12 gauge wire, which acts as a flame sensor.
Understanding the Propane Furnace Flame Sensor
The propane furnace flame sensor is designed to detect the presence of a flame in the burner assembly. It works by generating a small electrical current when exposed to the heat of the flame. This current is then used by the furnace’s control system to confirm that the burners are lit and the furnace is operating safely.
Technical Specifications
- Size: Typically about the size of a 12 gauge wire
- Material: Stainless steel
- Function: Confirms ignition of gas at first burner and flame travel to last burner
- Testing: Measures micro amps of current using a DC ammeter capable of reading 1-10 micro amps accurately
- Maintenance: Clean or replace if not producing correct amount of current
Troubleshooting the Propane Furnace Flame Sensor
When testing the flame sensor, it is important to measure the micro amps of current that the sensor is producing. This can be done using a DC ammeter capable of reading 1-10 micro amps accurately, which should be placed in series from ground to the sensor. However, it is essential to ensure that the ammeter can withstand the high voltage required to ignite the pilot light.
Checking Flame Rectification
During maintenance checks, it is also important to check for flame rectification (flame sensing). A good range for a flame sensor’s micro amps is typically between 4 to 6 uA. If the flame sensor is not within this range, it may need to be cleaned with fine steel wool or a green pot scrubber, and the burners should also be cleaned. If the flame sensor is still not within range after cleaning, it may be necessary to try a new rod or tighten the grounding connections.
Other Components to Consider
In addition to the flame sensor, other components that can affect the operation of a propane furnace include the thermocouple and the high limit switch. The thermocouple generates a small electric current when heated, which serves to keep the gas flowing for the pilot light only. The high limit switch measures the temperature in the vicinity of the heat exchanger compartment and interrupts the flow of gas if that area gets too hot. If the high limit switch is tripping, it may be due to something as simple as a dirty filter or blocked registers, or something more serious such as a leaking heat exchanger.
DIY Propane Furnace Flame Sensor Maintenance
Performing regular maintenance on your propane furnace’s flame sensor can help ensure its proper operation and prevent costly repairs. Here’s a step-by-step guide to DIY flame sensor maintenance:
- Turn off the power to the furnace: Ensure the furnace is completely powered down before proceeding.
- Locate the flame sensor: The flame sensor is typically a stainless steel rod located near the burners.
- Disconnect the wire: Carefully disconnect the wire from the flame sensor.
- Test the micro amps: Use a DC ammeter capable of reading 1-10 micro amps accurately to measure the current produced by the flame sensor.
- Clean the flame sensor: If the flame sensor is not producing the correct amount of current (4-6 uA), clean it with fine steel wool or a green pot scrubber.
- Reconnect the wire: Carefully reconnect the wire to the flame sensor.
- Turn the power back on: Restore power to the furnace and check for proper operation.
Remember to regularly check the flame sensor during routine maintenance to ensure it is functioning correctly and to address any issues promptly.
Conclusion
The propane furnace flame sensor is a critical component in the safe and efficient operation of a propane furnace. By understanding its technical specifications, troubleshooting techniques, and performing regular DIY maintenance, you can help ensure your furnace is running at its best and avoid costly repairs. Remember to always prioritize safety when working on your furnace and consult a professional if you are unsure about any aspect of the process.
References
- Checking Micro Amps on Flame Sensor
- Gas Furnace Flame Sensing
- Is This My Furnace’s Flame Sensor?
- Gas Furnace Flame Sensor
- Flame Sensor Troubleshooting
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